Recovery of valuable materials from waste liquid crystal display panel |
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| Authors: | Jinhui Li Song Gao Huabo Duan Lili Liu |
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| Institution: | 1. Department of Environmental Science and Engineering, Tsinghua University, China;2. Sino-Italia Environmental Energy Building, Room 804, Haidian District, Beijing 100084, China;1. Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia;2. Ecology Research Center, Research Organization for the 21st Century, Osaka Prefecture University, 1-1 Gakuen-Cho, Naka-ku, Sakai, Osaka 599-, Japan;3. Environment Research and Development Center, Environmental Protection Group, Sharp Corporation, 1 Takumi-Cho, Sakai-ku, Sakai, Osaka 590-8522, Japan;1. Institute of Circular Economy, Beijing University of Technology, Beijing 100124, PR China;2. Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada;1. Advanced Analysis and Computation Center, China University of Mining and Technology, Xuzhou 221116, China;2. School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China |
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| Abstract: | Associated with the rapid development of the information and electronic industry, liquid crystal displays (LCDs) have been increasingly sold as displays. However, during the discarding at their end-of-life stage, significant environmental hazards, impacts on health and a loss of resources may occur, if the scraps are not managed in an appropriate way. In order to improve the efficiency of the recovery of valuable materials from waste LCDs panel in an environmentally sound manner, this study presents a combined recycling technology process on the basis of manual dismantling and chemical treatment of LCDs. Three key processes of this technology have been studied, including the separation of LCD polarizing film by thermal shock method the removal of liquid crystals between the glass substrates by the ultrasonic cleaning, and the recovery of indium metal from glass by dissolution. The results show that valuable materials (e.g. indium) and harmful substances (e.g. liquid crystals) could be efficiently recovered or separated through above-mentioned combined technology. The optimal conditions are: (1) the peak temperature of thermal shock to separate polarizing film, ranges from 230 to 240 °C, where pyrolysis could be avoided; (2) the ultrasonic-assisted cleaning was most efficient at a frequency of 40 KHz (P = 40 W) and the exposure of the substrate to industrial detergents for 10 min; and (3) indium separation from glass in a mix of concentrated hydrochloric acid at 38% and nitric acid at 69% (HCl:HNO3:H2O = 45:5:50, volume ratio). The indium separation process was conducted with an exposure time of 30 min at a constant temperature of 60 °C. |
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